Many conventional sources of oil and gas production are on the decline. As a result, it has become more difficult and expensive to extract these reserves. To meet expected demand, the industry has increasingly focused on unconventional sources as it has become more technically and economically feasible to do so. According to the International Energy Agency, at least 10% of the remaining recoverable conventional oil and gas reserves lie below the seafloor in deep water. In offshore drilling operations, a drilling rig is typically used to drill a wellbore to recover oil or gas reserves disposed below the seafloor. The offshore facilities may include bottom founded, floating, or mobile drilling rigs and production platforms. In ultra-deepwater operations, drilling and production is conducted in water depths between 5,000 and 10,000 feet or more. Conventionally, offshore operations drill wellbores having a measured depth in excess of 10,000 feet.
The Lower Tertiary is an informal designation for a layer of the Earth's crust deposited during the Paleogene period, between 65 and 23 million years ago. The Gulf of Mexico's Lower Tertiary is considered one of the largest ultra-deepwater oil and gas reserves. According to recent estimates, the Gulf of Mexico's Lower Tertiary is believed to contain between 10 and 40 billion barrels of oil equivalent (“BBOE”). This is significant given that the total estimate of U.S. oil and gas reserves is currently estimated to be approximately 30 BBOE. However, extracting oil and gas from the Lower Tertiary presents a number of technical and economic challenges. To access these reserves, ultra-deepwater drilling operations must deal with water depths up to 10,000 feet or more and drill a further 15,000 to 30,000 feet or more below the seafloor, often under thick sheets of salt, to reach Lower Tertiary reserves. At depth, the downhole temperature may exceed 400° F. and formation pressure may exceed 25,000 pounds per square inch (“PSI”) further complicating production activities, including chemical injection.